Conventionally, in endovascular treatment, angiographic examination, and the like, a catheter is inserted into a blood vessel, for example, from the base of a foot, and is brought to a target site via the blood vessel. When the catheter (or a guide wire that guides the catheter) is brought to the target site, an X-ray fluoroscopic image is displayed. Watching the displayed image, a user moves the catheter or the guide wire to an affected site.
In an X-ray diagnosis apparatus, an X-ray tube and an X-ray detector (which is generally a planar detector called FPD) are so disposed as to face each other, and, on a front of the X-ray tube, an X-ray beam limiting device is provided. The X-ray beam limiting device includes collimator blades that can slide. As the collimator blades are moved, a diagnosis area of a subject is selectively irradiated with X-rays. In this manner, the X-ray diagnosis apparatus is designed to protect the subject from unnecessary X-ray exposure.
However, the X-ray beam limiting device can move only in a horizontal direction (X-direction) and a vertical direction (Y-direction) with respect to FPD. If a blood vessel region that a user wants to see extends diagonally with respect to FPD (e.g., a blood vessel at the base of a foot), the problem arises that the irradiation field becomes larger, causing unnecessary exposure.